| 摘要 |
PROBLEM TO BE SOLVED: To detect the load condition when an output stage MOSFET becomes ON by pulling down a gate terminal to low potential during the OFF term of a semiconductor switch element, and connecting a second input to low potential. SOLUTION: By an ON signal, charge current flows in the route of gate resistance 12 → capacity 18 between gate-source → load 4 to raise output. After the lapse of a fixed time, by reduction of the charge current, the output once reduces, but when the gate potential of an output stage MOSFET 2 reaches threshold voltage, the output rises again. Because the charge current flowing the capacity 18 between gate-source reduces by increase of time constant due to increase of load impedance, the time at which the gate potential of the output stage MOSFET reaches the threshold voltage is delayed. Output during time from ON point of input to beginning of timer set in a timer circuit 61 is detected. |
